ATOMIC_CAS_UINT(9) BSD Kernel Developer's Manual ATOMIC_CAS_UINT(9)
NAME
atomic_cas_uint, atomic_cas_ulong, atomic_cas_ptr  atomic compareand
swap operations
SYNOPSIS
#include <<sys/atomic.h>>
unsigned int
atomic_cas_uint(volatile unsigned int *p, unsigned int expected,
unsigned int new);
unsigned long
atomic_cas_ulong(volatile unsigned long *p, unsigned long expected,
unsigned long new);
void *
atomic_cas_ptr(volatile void *p, void *expected, void *new);
DESCRIPTION
The atomic_cas set of functions provide an interface for atomically per
forming compareandswap operations with respect to interrupts and multi
ple processors in the system.
The value referenced by the pointer p is compared against expected. If
these values are equal then new replaces the value stored at p.
CONTEXT
atomic_cas_uint(), atomic_cas_ulong(), and atomic_cas_ptr() can all be
called during autoconf, from process context, or from interrupt context.
RETURN VALUES
These functions return the value at p as it was before the attempt to
swap it.
SEE ALSO
atomic_swap_uint(9)
HISTORY
The atomic_cas functions first appeared in NetBSD 5.0 and OpenBSD 5.5.
BSD July 18, 2014 BSD
